Solid-state lighting devices have many uses in residential and commercial applications. Some types of solid-state lighting devices may include laser diodes and light-emitting diodes (LEDs). Ultraviolet (UV) solid-state lighting devices may be used to curing photo sensitive media such as coatings, including inks, adhesives, preservatives, etc. The curing time of photo sensitive media may be sensitive to the intensity of light directed at the photo sensitive media and/or the amount of time that the photo sensitive media is exposed to light from the solid-state lighting device. However, output of solid-state lighting devices may vary with device junction temperatures and other conditions such that it may be difficult to provide uniform output during the curing process. Consequently, it may be desirable to provide more consistent and uniform output from the lighting devices so that work piece curing time may be more precisely controlled.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for operating one or more light emitting devices, comprising: in response to a step change in requested output of the one or more light emitting devices, adjusting current supplied to the one or more light emitting devices responsive to one or more parameters based on output of the one or more light emitting devices when a step change in voltage or current is applied to the one or more light emitting devices, the step change in voltage or current not occurring at a same time as the step change in the requested output of the one or more light emitting devices.
By controlling current flow through a lighting array based on response of the lighting array when a step current or voltage is applied to the lighting array, it may be possible to more precisely follow a step request in lighting array output. Consequently, a more uniform output from the lighting array may be output during operation of the lighting array. For example, output of a lighting array may be more intense when the lighting array is initially activated in response to activating the lighting array. However, as time goes on after initial activation, output from the lighting array may decay and converge to a desired lighting array output. Parameters such as percent of irradiance overshoot initially relative to steady state irradiance output and time for the lighting array to reach half way to the steady state temperature light output when the lighting array is activated via a step change in voltage or current applied to the lighting array may be a basis for controlling current flow into the lighting array such that output of the lighting array (e.g., irradiance) approaches a step change in desired lighting array output. Thus, an unregulated response of a lighting array may be a basis for regulating output of a lighting array.
The present description may provide several advantages. Specifically, the approach may improve lighting system output consistency. Additionally, the approach may be provided without attempting to feedback lighting system output, thereby simplifying lighting array current control. Further still, the approach may be provided to both step increases and decreases in requested lighting system output.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.